Article: Cleaning the Throttle Body

The throttle body is a pretty simple component but after years of service the internal passages can become clogged/dirty & the TPS (Throttle Position Sensor) begins to fail. For these reasons I recommend cleaning the throttle body and replacing the TPS on any van with 150k or more miles. Here's my method of disassembling, cleaning, and adjustment.

This is a throttle body I pulled from a parts van. It will take a couple days soaking in Chem-Dip, so I can drive my van while this is being worked on, then I can swap it out with the one on my daily driver when it's ready.

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Chem-Dip is a pretty harsh cleaning chemical. So harsh that it will eat rubber & plastic parts. Before soaking the throttle body in this it must be disassembled. Toyota didn't intend for these throttle bodies to be easily disassembled, but I have worked out a way to get the job done. The 1st challenge is the screws holding the butterfly to the throttle shaft. After installation Toyota crushed the threaded ends of these screws against the side of the shaft. To make matters worse, they used an unusual screw size (M3.5 X 0.6). So unless you plan on drilling & re-tapping the throttle shaft (to accept a more common screw size), you will need to save & re-use these.

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Use a Dremel with a metal cutting fiberglass/abrasive wheel to carefully grind the crushed portion of the screws off. Don't stop until they are flush with the shaft. It will save you time later to also make an identifying scratch in the butterfly so you can orient it the same way when it's time to go back together.

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While you have your Dremel out grind some slots to allow removal of the idle adjust screw cover.

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Now it's time to remove the TPS........just two screws and it pulls straight off the shaft.

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Next remove the nut, the cable guide, throttle return spring, and other associated parts from the throttle shaft. Take a picture or make notes so you can put this back the same way later.

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Now the 3.5mm screws can be removed from the shaft & the butterfly can be removed. Note: These screws are a bit "soft" so be sure to use a high quality #2 Phillips screwdriver bit & make sure the tip is in good condition. Bear down hard on the screws when you rotate. You will only get one shot at this & these screw heads strip out easy. Sometimes the crushed threads extend up in the shaft area a bit so occasionally these screws are hard to remove. Remember when I said "you'll only get one shot at this"?...........well I might have lied just a little :wnk:. That was to get your attention so you'd try your best! :yes:. Sometimes even when you do everything right the heads still strip :(:. When this happens use your Dremel to make the Phillips heads into slot tips. Remember, you will still want to re-use these & this is your last shot..........unless you drill and tap for new screws........so be careful and do a good job. After the screws are out remove the butterfly.

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Now the throttle shaft can be removed.

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Take a slot tip screwdriver and gently pry out the throttle shaft seals.

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These typically pop right out.

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When it comes to your idle adjust screw, get a slot tip screwdriver and while counting revolutions, turn it clock-wise until it bottoms out. Record the number of turns for future reference and then remove it. Sometimes the rubber o-ring will make it difficult to remove. If you have one, a screw holding screwdriver works well for extracting the idle screw. If you don't have that then it can be "blown out" by using compressed air through the exit port. If you use the compressed air method cup your hand under the screw so you don't lose it. Once removed, carefully remove the rubber o-ring from the idle screw and save for later. The other parts on the throttle body are pretty self explanatory. If you don't already have some, go to your local parts store and get yourself a gallon of Chem-Dip. Remember this stuff is nasty so read the directions and avoid skin contact. Load all the metal parts into the basket (included inside the gallon container) and lower into the can. Put the cover back on the can and forget about it for a couple of days. Hint: Chem-Dip will eat almost anything, but it will work better if you remove excess dirt before dipping. Also, I recommend scraping/cleaning all old gasket material prior to soaking. Soaking won't always remove gasket material so it's better to get it off before hand. Another thing to consider is how long you may want to keep/use your Chem-dip. The more junk it eats-up the less effective it becomes. The can I'm using now is one I've had for over 10 years. It's getting weak, but it still does the job.

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Okay, so a couple days have passed, now it's time to get back to it. Use a pair of pliers or a wire hanger to hook the basket and pull out of the Chem-Dip. Have another container of an appropriate size ready to set the basket in. I use Mineral spirits to dilute and remove the residual Chem dip. After the parts are covered with mineral spirits I agitate the basket to rinse. Now parts can be removed one at a time and a parts cleaning brush is used, then compressed air to blow dry.......Be sure to use eye protection!

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Could these be the same parts I had before? :thmbup: Okay, the TPS is new, but everything else is original!

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The old shaft seals will usually push right in with just thumb pressure. I'm using a synthetic lubricant with PTFE to lubricate the throttle shaft seals & bores.

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After installing the throttle shaft & aligning the butterfly, I clean the burrs off the shaft screws threads & apply some semi-permanent Lock-Tite.

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Screws are installed but left loose. Before final tightening allow butterfly to self center by closing throttle all the way & then tapping on it & the shaft. The periphery of the butterfly is precision machined at an angle to match the inside of the throttle body, so Make sure it's oriented correctly! Without the throttle stop assembled, while closed it should make an air-tight seal. Hold it up to the light to verify it's centered & intimate with the throttle body bore. Once you're satisfied tighten the screws.

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O-ring is installed on idle screw and lube applied.

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Idle screw is installed & bottomed out. Next we back it out the number of turns previously recorded.

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Throttle shaft built up with return spring, cable guide & associated parts. Nut is installed and tightened.

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New throttle position sensor is installed & other misc pieces of throttle body are put back like before.

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And here's the end result :dance2:.

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Now that the throttle body is reassembled the only thing left to do is adjust the TPS & install it on your van. Here is a video on how to do this (click on the image below to view video).

https://youtu.be/Ku1EMEYRMgk

Before you install check the condition of the throttle body coolant hoses. If soft or deteriorated now is a good time to replace. I suppose a bulk 5/16" or 8mm hose could be used here, but the bends are rather tight and you may end up with a crimped hose. Last time I needed these they were still available through Toyota. They are part #16267-73010 & 16264-73021. You'll also want a new throttle body gasket & that one is Toyota part ##22271-73011 & sells for ~$5. Tim

i have an 87 4wd five speed :) and it has a dashpot on the throttle body. what exactly does this do?

It's an emission device. It's job is to delay return to idle while you are decelerating. For some reason that reduces emissions. Occasionally you will find one that sticks and/or will not allow the throttle to return to idle at all (this is usually what happens when they fail). These are NLA from Toyota & haven't been available for some time. If you find a bad one just take it off and throw it away (bad ones do more harm than good). I like keeping things original so whenever I find 5 speed vans in the salvage yard (which is hardly ever) I always take the dash pots and save them.

For those of you who don't know what the dash pot is, here's a picture of one from a previous throttle body I cleaned. It's the black component in the top right of the picture below:

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I will be remembering this thread :thmbup: . I saw that my carb on the '88 that I got was pretty dirty, when I had the head off. I just sprayed the crap out of it with carb cleaner and brushed and scraped it as best I could (assembled). The finished product in your case is really looking good. I almost hope I have trouble now, so I can take it back off and do it right :)

For anybody planning to do this, I thought I'd mention it's a very good idea to have a M3.5X0.6 tap & same size die available before hand. As stated earlier this is an uncommon thread size & I wouldn't expect to find these in a regular tap & die set. After you get the screws out of the shaft use the tap to clean-up the shaft threads & the die to clean-up the screw threads. In my experience the tap & die are much easier to find than new screws. Here's a couple links to them on eBay:

http://www.ebay.com/itm/3-5mm-x-6-Me...item19ca996ff3

http://www.ebay.com/itm/Hanson-Whitn...oAAOSwZd1VcmBc

In case those links go bad, here they are again on Amazon:

http://www.amazon.com/3-5mm-Metric-T...M3.5+x+0.6+tap

http://www.amazon.com/New-3-5mm-Metr...M3.5+x+0.6+die

Nice article! Couple of question:
Did you replace the shaft seals or were they in good enough shape to reuse?
Are all of the throttle bodies interchangeable? Like, could I grab one off an '85 automatic, rebuild it, and put it on my '89 5-speed? I only seem to find early vans in the junkyards.

I've probably done a dozen of these so far and have never found bad seals. Before I did the 1st one I searched for seals but other than the TPS Toyota doesn't break the throttle body down or list individual parts. If I recall correctly you can get aftermarket heavy duty seals for some of the other Toyota throttle bodies (for guys running turbos & superchargers). I suspect they would be the same diameters but don't know that for sure. Since these seals are fairly well sheltered & because they are easy to remove/reinstall I have always just re-used. Perhaps I've been lucky but these don't seem to get much wear & tear.

All vans 84-89 use the same throttle body. The only variable is manual transmission vans have a dash pot & the autos do not. The casting of the body is the same on all so you could always take the dash pot off one & add it to another. I did a cross reference with the EPC and according to that this particular throttle body was only used on the vans. I suspect there may be some other throttle bodies that may interchange, but not sure what the differences would be.

If you were looking to adapt a throttle body from another application, the vehicles listed below would likely show the most promise (these use the same TPS as the van). Tim

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i have a few questions, too.
If the idle air screw has been monkeyed with, is there a specific number of turns that it should be? on a particular lpg regulator on a forklift it is 4.5 turns from bottom, but that is just a starting point,it is usually adjusted about a half turn either way, if the other components in the system are in correct specs.

also the throttle stop screw was loose so where should it be???

I am trying to adjust the TPS on an extra throttle body, so I can just swap them out (CEL is showing the tps code) but my meter doesnt do sound. what range setting should I use? with out the leads attached, it shows 000, then if i touch them together it blinks a bunch of numbers, and then shows 001??? i am lost

The factory setting for the idle adjustment screw is approx 1 3/4 turns CCW after being bottomed out. The idle stop screw is set to hold the tang of the cable guide approx .095 away from touching the aluminum tab the stop screw is threaded into. Regardless of what meter you use & it's accuracy, when set to ohms it will at least tell you the difference of continuity vs no continuity. Continuity is what it reads when the probes are touched together, no continuity is what it reads when the probes not touching. Regardless of what yours says when probes are touching, that's what you should see when you find that "magic spot". Keep in mind you're seeking out the illusive spot where it transistions from continuity to no continuity, so your meter could fall on either side of the transistional spot. Even if it's a tad off, you'll still be "in the zone". If your meter is not quality enough to tell the difference between continuity/no continuity, then perhaps it's time to find another meter. Tim

lol yes, tim, it is time for a nicer meter, i have a nice older craftsman, but the fuse that does resistance is out, and i cant find a suitable replacement fuse. i think maybe the old tps i have is bad, but cant confirm it. i found a sweet spot using the 2000 ohms setting, but when i re tested it it failed.

thank you for the response, where did you find that info, by the way? is it in the manual?

I've gone through a few throttle bodies and was able to remember the idle set screw setting. For the throttle stop setting I grabbed an extra throttle body I have laying around with the anti-tamper paint still on the idle stop screw & I measured it :D. Then just for kicks I bottomed out the idle screw & verified 1 3/4 turns :thmbup:.

As for older TPS units, unless you know how many miles it has (and it's under 100k) I wouldn't trust it. Over time the contacts inside become "iffy". If it still completes the circuit(s) it will likely connect at different spots each time you cycle the throttle. If you're trying to save money, you might try aftermarket. The last 5 or 6 of them I've installed were Beck Arnley #158-0503 & they seem to be quality units. So far none have given any issues. I usually stock up on them when RockAuto has a sale (around $20 each). Their normal price is around $35 each. Tim

calibrated new TPS this evening, removed old throttle body, and found that it has been disconnected for years. the contacts in the plug were green with corrosion. supposedly this engine was swapped in from a 4wd 5speed, but there is no dashpot.......I imagine he just didnt know it was unplugged. Now I have a clean throttle body, with a new sensor. van starts and runs better than ever, just need to replace coolant temp sensor, and reset my timing and i think it will be great. Thanks Tim!

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Originally Posted by gushaman

calibrated new TPS this evening, removed old throttle body, and found that it has been disconnected for years. the contacts in the plug were green with corrosion. supposedly this engine was swapped in from a 4wd 5speed, but there is no dashpot.......I imagine he just didnt know it was unplugged. Now I have a clean throttle body, with a new sensor. van starts and runs better than ever, just need to replace coolant temp sensor, and reset my timing and i think it will be great. Thanks Tim!

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Awesome! :dance1:. That's certainly not the 1st time I've seen a TPS disconnected. I did this job once & then went check my timing & could get no advance when I pulled the "check engine connector" jumper. I also noticed it was blinking a TPS code. I was like "damn, I got a bad TPS".........that's when I noticed the TPS connector dangling there :LOL2:. I felt stupid but at least it was an easy fix. All issues were quickly resolved when I plugged that connector back in :yes:. Tim

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Originally Posted by timsrv

Awesome! :dance1:. That's certainly not the 1st time I've seen a TPS disconnected. I did this job once & then went check my timing & could get no advance when I pulled the "check engine connector" jumper. I also noticed it was blinking a TPS code. I was like "damn, I got a bad TPS".........that's when I noticed the TPS connector dangling there :LOL2:. I felt stupid but at least it was an easy fix. All issues were quickly resolved when I plugged that connector back in :yes:. Tim

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Just noticed my TPS was also disconnected this morning. Im gonna try to connect it back later today and see if I can zip tie it to the TPS to prevent it from being disconnected again.

Question... If the TPS is bad, will the check engine light come on? Or could a bad tps never signal the check engine light to come on? I think I have put more then 150K on my van since I replaced this 5-7 years ago.

A bad or disconnected TPS will trigger a code inside the ECU but may not necessarily make your "check engine light" illuminate. To read codes you'll need to jump the CEL connector & count the blinks. Since it's been disconnected you will likely have a TPS code, so you'll need to clear that and drive for a while to see if it comes back. If it doesn't, then you're golden. Tim

PS: These connectors are pretty solid as far as accidentally falling off. If yours is doing this it's either damaged or missing the little locking spring clip.

I just did another one of these and this time destroyed both screws. I was able to drill & remove without damaging the threads on the shaft. Then I got lucky enough to find some replacement screws on eBay. I estimate the originals to be 10mm in length, so these will likely be a tad long (12mm). Still, this diameter & thread size is rare, so I feel lucky to have found these (can always be shortened if necessary). Here's a link: http://cgi.ebay.com/ws/eBayISAPI.dll...E:L:OC:US:3160. Since I had to buy 100 of them, I'll probably never need them all. If anybody else runs into this issue and needs some screws, PM me your address and I'll mail you a couple. :D Tim

Tim what are you using for TPS replacement these days? I searched pretty hard on toyotapartszone for one the other night and couldn't find it.

We have discussed this a few times here, and again just a few days ago. This is a good thread for this discussion though (better than the other places it's been posted). Here's a few quotes from the last time it was discussed. Tim

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Originally Posted by timsrv

Clear codes, drive it some more & recheck codes. If #51 comes back you most likely have a bad TPS. These are a common failed part on the van. If it's got more than 150k miles on it or if you don't know how old it is, then I'd just replace. Testing these per the manual is a somewhat involved process. I'm not saying he didn't do it right, but it's hard to imagine your average mechanic going to this much effort (it would be hard to do with the throttle body installed). Even if he did do everything right, when these get old they become intermittent. Bottom line? For a $35 part it's not worth messing with. I replace these like some people replace spark plugs. If I'm doing a tune-up and I see code 51, I won't even mess around with trying to clean or whatever. Just replace it and be done with it :lol:. Tim

PS: If it's newer and you know it's got less than 100k miles on it, then perhaps it's worth a little more consideration. But for me, my time is more valuable than messing with a questionable TPS. Tim

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Originally Posted by kestrel

thanks, tim. i'm going to do it. i see that the part on 1sttoyotaparts.com is almost $70 and on rockauto.com is $32 (beck/arnley). that's a big difference. is it worth spending the extra bux for the toyota part?

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Quote:

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Originally Posted by timsrv

I used to think so, but a while back www.rockauto.com had one of their "closeout" sales and I picked-up "the last 6" of the Beck Arnley #1580503 units for $18 each. Of course they weren't the last 6 (but were certainly the last 6 I've seen at that price). I took the cover off the 1st one and inspected before installation (thought it looked good). These Beck Arnley units are made in Italy (not sure if that matters) & appear to be of high quality. That was about 4 years ago and I've since used them all (and then some) on different vans I've worked on. I just ordered another one last week (sucked having to pay ~$35 for it), but it's a lot better than $70 something from Toyota. Unless these aftermarket ones start dropping dead, I'm not buying any more from Toyota. Tim

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BTW, the last one of these I got was off of Amazon http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1. It's listed for a few cents more, but if you have Prime shipping is free and it will show up in just a couple days (so it's a better deal overall). If you click on the link, ignore the picture in the Amazon listing (it's wrong). The part you get will be the correct one. Tim

Quote:

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Originally Posted by timsrv

Then I got lucky enough to find some replacement screws on eBay.

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For future reference, Mcmaster Carr has these screws with a variety of head types. I'm always amazed by how much weird stuff they have and how fast they're able to ship. I think you need to set up a business account with them, but last time I did that I just used the name and address I worked at and used my own credit card with no issues.

I always forget about these guys. I used to purchase a lot of stuff through them when I was a tool maker. It's amazing how much stuff they have. Thanks for pointing that out. Tim

i will be doing this soon! Awesome write up

Just a quick question for those of you that have removed/installed TBs :

how necessary is it to drain the coolant before pulling the TB? the manual says to drain it, but I just put all that darn stuff back in there!

will I get a few bits of spillage, or am I looking at losing it all anyway if I don't drain it.

Fortunately the throttle body is the high point in the system. I would pull the radiator/filler cap & drain about a cup out of your radiator petcock. After that you should be able to pull the TB hoses & work on it with little more than a few drips. Tim

I thought you only had to drain the coolant if you remove the upper intake manifold?

the two hoses on the throttle body are by-pass hoses and will hardly leak at all.... Tim is right tho just drain a cup or so

I wound up draining about a cup of coolant. When the TB finally came off, no extra coolant spilled out.

The two bypass hoses are pretty worn looking, so we'll go for some new ones.

With everything off, I'm thinking about replacing the vacuum hoses for the TB. They all read #0 which I'm guessing is the size of the hose?

Here's a quote from another thread:

Quote:

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Originally Posted by timsrv

Regarding the vacuum line (the small stuff like what runs across the top of the throttle body), this can be substituted for standard aftermarket sizes at the parts store but I've found the fit isn't perfect (either too small or too big). The small is more secure and less likely to fall off, but pushing it over the nipples stretches it a bit beyond it's design limitations (makes it prone to cracked ends). The other problem is the little looms that fit over the hose (for organization) don't fit the aftermarket stuff right. For this reason I prefer Toyota vacuum hose. Toyota sells it in predetermined lengths from 300 mm (about 1 foot) to 2600 mm (about 8 1/2 foot). Here's the Toyota part numbers & current pricing (at the time of this post):

• 90999-92002 300mm $5.46 (~$5.46 per ft)
• 90999-92003 600mm $2.53 (~$1.26 per ft)
• 90999-92004 950mm $13.33 (~$4.44 per ft)
• 90999-92006 1300mm $21.38 (~$5.35 per ft)
• 90999-92007 1650mm $36.78 (~$7.36 per ft)
• 90999-92008 2600mm $52.18 (~$6.14 per ft)

Note, this is current MSRP (what you'd pay if you walk into your local Toyota parts counter). If you order it via one of the discount Toyota parts sites, you can save up to 30% (before shipping), but as you can see, the cheapest way to get is purchasing in 600 mm lengths (about 2 ft). The good news about this size vacuum hose is Toyota uses it on almost everything they make so they're not likely to run out any time soon. Tim

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my latest and most current need for help is with the throttle body rebuild. everything is off and ready to go into the chemical bath but... the screw under the rubber cover (idle screw) backs all the way out but stops short by 1/4" of coming out of the hole. i've tried air- but with no joy. the screw just spins after backing it out. it will tighten back down each time but after several tries to unscrew it, it just wont go that last bit so i can get a grip on it. what am i missing in the process?
i'm stumped. anyone have any suggestions?
thanks- mike

I assume you've already read the 1st post in this thread.........right? That screw has an o-ring on the head, and it grips the bore (makes it hard to remove). I use a screw holding screwdriver & it comes right out every time, but if you don't have one it might be a PITA. Air should work, but it can be difficult to seal your air gun against the port. A rubber tipped air nozzle would work much better than a standard one. Tim

thanks tim for the soft knock on the head. i do remember reading the post with the link and thinking - wow , i finally get to use my starter screw driver after all these years its sat in my tool box neglected.
it must be that forest and the trees thing. or more likely the aging process at work.
i got it out in seconds. thanks
where can i pick up a gasket for the t body, toyota wants too much and will take too long. do any other vehicles use this same t body gasket - do you or anyone know? also what is the name of the lube with pfte you use for the seals and o-ring.
my idle screw was 1 3/4 turns to bottom. sound about right. how would one remedy this once installed without pulling it apart again? would this keep it from starting or just idle crappy??
thanks as always for the assistance. - mike

If you don't want the Toyota gasket, then start calling auto parts businesses. I'm guessing it's a dealer item, but somebody might have one. If you find one on the cheap, please post so the rest of us will know too. There's always the paper stuff they sell for cutting out your own gaskets too. That lube I'm using is Radio Shack part #64-2301A. I use it because I like the applicator, but I'm sure others will work just as well. I've had it for years, so wouldn't surprise me if they don't carry it anymore.

That screw is simply to make fine adjustments to your idle speed. 1 3/4 turn is just the starting point or approx setting. If it's off, the worst that can happen is your idle RPM's might not be exact. It won't affect starting. Once it's been warmed up and the timing has been set, you use that screw to set the idle speed. Tim

greetings
i assembled the t body and hit a stumbling point. or maybe everything is as it should be. my t body was encrusted with carbon and black soot at the start so i could not tell to note whether or not my finished job is correct or not.
it appears to work as intended but the shaft and disc come to rest at an angle a little less than 45 degrees. it does not close flush.
looking down thru the top of the throat, with the body oriented with the water hose side facing me the disc is angled downward towards me and the screw slots are facing me.so i know the shaft is installed correctly. the shaft and disc come to rest disc high in the rear angled downward toward me. at this point there are little air gaps at top and bottom and appear to be even in size.
should these gaps at the rest point be there at all or is this normal, and is this angle of the disc at rest normal.
when i started the assembly after cleaning i placed the brass disc into the bottom of the throttle body flat by itself to see if it fit and to check the tolerances around the circumference. it fit perfectly into the opening only one way and matched my marks exactly
i pushed the disc flat into the body and it stopped passage at about 1/4 inch into the throat. i installed the shaft and placed the disc into the body throat, i had to tap it lightly down with the butt end of a wooden hammer to get past this sticky point and into the slot of the shaft ok. with it loose in the shaft slot i installed the screws loose and floated the disc while moving the shaft to find the sweet spot. i then snugged the screws up. the shaft will not close any further than described above.i repeated this procedure several times with the same results.
i finally gave up and finished the assembly and this is currently how it now sits on my bench.
i hope i have written a description clear enough for others to interperit ok. i know this could become a wordy dialogue so if you want my number instead of writing send me a pm and ill get it to you asap.id sure like to move on with this task done and behind me in working order.

anybody have any advice on this? is it right as it sits or does something else needed to be done. did i miss a step?
thanks - mike

p.s. FYI on the removal of the stuck/stubborn idle screw- i could hear the dry o ring squeaking so i screwed it back down added some drops of mystery oil, turned the screw in and out a few times and it smoothed the screw right out of the hole.

The butterfly plate in the throttle body is precision machined to make an air tight seal. Even the edges are machined at an angle to match the inside bore. To start with, the shaft & the butterfly plate need to be oriented the exact same way they were before you disassembled (each side facing same direction and top and bottom same as before). This is why I suggest scratching an identifying mark on the plate before disassembling (allows for easy and correct alignment while assembling). When the butterfly and shaft are oriented as before, prior to tightening the screws, you close it tightly so it fits intimately with the throttle body bore. With the throttle held tightly closed, you tighten the screws to lock in place. If the butterfly will not close tightly against the bore or if you did not seat it as described, you'll need to go back and do it again. If you made no marks on the butterfly before disassembling, you'll need to fit it each possible combination until you find the one that allows it to close all the way and make an air tight seal. Good luck. Tim

Note: Always set the butterfly to the shaft BEFORE putting the cable guide or any other parts on the shaft. Other parts (like the idle stop screw or TPS) will interfere with correctly setting the butterfly.

I would like to contribute the following solution you might need, related to this cleaning job.

I cleaned my TB and then the engine would not idle down. It turns about that the butterfly would not totally close does due to wear in the shaft bushings (or somewhere else perhaps) and it would bind a little. And I found that it would close if there were some pressure on the shaft, the pressure being placed at the tip of the shaft so as to push it back toward the TPS. So I fabricated a 1/2 wide steel bar with a large hole and a small hole about 2.75 inches long. The large hole allows it to slide over the threaded end of the shaft, and then putting the original nut back on, it sticks straight up at idle but does not touch the engine lid. The small hole has a tension spring running back to another similar bar I have sticking up from the upper rear TB bolt. So the spring is parallel to the shaft, pulling the shaft toward the TPS. There is not really all that much tension on the spring, and it does not significantly effect the effort required to increase throttle. I can feel no difference at all actually. The fix works beautifully though it is rather hack like. It cost about $2 for the springs and bar stock might be less than $10 from a hardware store.

Hey Tim
I'll probably never have a use for the throttle body that came on my used motor from Japan, I'd happily send it to you for the help I have gotten from this site.
Donny
93 previa
PS
I was getting an extra 4 miles to the gallon with this motor...... 25 mpg highway avg 65 on flat ..... left the injectors in it that it came with from japan, as well as intake manifold. I believe......
PS
can you send me the link to reading engine codes on the baby
thanks probably o2 issue.

found the codes from an old post thanks though
just let me know on the throttle body
donny

Thanks Donny, that would be cool. I'll PM you my address. Tim

Found a website selling the TPS at 11.99 a pop. But not sure of website...I'm kinda paranoid giving out my info these days...

http://www.brohacks.com/72discount20...r-p-12508.html

Yeah, I put 5 of them in my cart and went to check-out. Before entering any personal information I checked and found it was not a secure page. If they would accept PayPal I would have completed the purchase, but there's no way I'm giving out my info on an insecure web page. If anybody else wants to take a chance, get me 5. If they actually show-up I'd be happy to pay you $20 each + shipping. Tim

Oh, and the website address "brohacks" doesn't instill a lot of confidence :dizzy:

Yeah I put in a fake name to get to checkout. It ran my order and said I owed payment in iTunes gift cards. Someone might be bummed when "Mr.Frankenstien" at "12345 Sesame St." doesn't pay up...

Tim,

i have the throttle body in my hands and i'm watching your video how to adujst TPS. On my 1988 repair manual, the values for continuity and discontinuity are 0.0224 and 0.0335. Why are you using different gauge thickness for checking continuity (0.028)?

Also, inside the intake is full of black stuff. what do you suggest to remove it?

thanks a lot

Jerome